A market exists for incompletely/partially manufactured firearm lower receivers. A firearm lower receiver is unregulated until a minimum level of manufacturing is completed. This level is typically known as “80%”. Firearm lower receivers completed to this level are typically referred to as “80%” lower receivers. These firearms must then be completed by the end user to be operable. In a typical configuration the lower receiver is cast and/or forged and is partially machined, with certain aspects of the inner slot (in which the trigger mechanism resides) remaining uncut. The finishing task cuts this remaining slot with appropriate dimensions and accuracy.
The completion of these lower receivers can be time consuming and quality results may be difficult to achieve with prior art. In accordance with the prior art, the technique for finishing the receiver can place a rotary power tool in a position that is effectively too far away from the lower receiver. As such this prior art technique can produce poor results and broken tooling. Additionally, the prior art technique can involve placement of a rotating tool in direct contact with guiding areas of a jig, which can result in premature wear.
It would be desirable to provide a jig assembly that effectively reduces the unsupported distance between the rotary power tool and the 80% lower receiver and that avoids direct contact between the rotating tool and its guiding features.